Possible interaction between ciprofloxacin and warfarin.
A 72-year-old man had been taking warfarin for a pulmonary embolus and recurrent deep-vein thromboses. His prothrombin times (PTs) were maintained between 15 and 18 sec (PT ratio 1.25-1.5 x control) for several months on a dose of warfarin 2.5 mg/d. Six weeks prior to starting ciprofloxacin 500 mg bid, the patient's PT was 15.5 sec (Pt ratio 1.29 x control). After one week of ciprofloxacin, his PT had increased to 22 sec (PT ratio 1.83 x control). No other causes for the increase were apparent. It is recommended that patients receiving both medications have their prothrombin times carefully monitored and warfarin doses adjusted only as necessary.
Kamada
A K
AK
Pharmacy Service, Veterans Administration Medical Center, Denver, CO.
D000368:Aged; D002939:Ciprofloxacin / Q000009:adverse effects* / Q000627:therapeutic use; D004347:Drug Interactions; D006801:Humans; D008297:Male; D011517:Prothrombin Time; D011655:Pulmonary Embolism / Q000188:drug therapy; D013924:Thrombophlebitis / Q000188:drug therapy; D014859:Warfarin / Q000009:adverse effects* / Q000627:therapeutic use
D002939:Ciprofloxacin; D014859:Warfarin